I can confirm that if you are using a TA, that you cannot modify that reservation. I ask my TA and she said she could only modify my reservations and that I could not. Keep in mind, I am an anxious control freak, and I have never used a TA before, but this one came highly recommended. When it was 180 days before our trip, she managed to get every TS reservation we wanted, including : character dining reservations (4 total: Cinderella's Royal Table, Ackerhaus, 1900 Park Fare, and Rivers of Light Pkg at Tusker House), La Hacienda San Angel at 8:00 to watch Illumination at Epcot, and Fantasmic pkg at Mama Melroses. These were all for a table for 7 people. She also secured a reservation for my 2 grandaughters age 6 and 8 at Biddidy Boddidy Boutique before we eat At Cinderella's Royal Table. She did all this and had an email to me by 7:10 A.M. on the morning of the 180th day before we leave. However, even knowing that she has done a great job so far, I am still very anxious about the FD because of the rumor saying mods will only be getting QS. We are booked in 2 rooms in Pop and feel that many may abandon mods and book at value. So good luck to all and don't feel like you are alone in playing this waiting game.